Embodiments of the present invention relate generally to a power flow in a power system. More specifically, the embodiments relate to damping of power system oscillations.
The power system is a complex network comprising of numerous generators, transmission lines, a variety of loads and transformers. With increasing power demand in the power system, some transmission lines are more stressed than was planned when they were built. Since stressed conditions can lead a system to unstable conditions, power system stability has become an important issue. In simple terms, power system stability is defined as the ability of the power system to return to a normal state after a disturbance. The disturbance may be a fault, a loss of a generator or even a sudden increase in power loading which results in power oscillations in power system.
Most of the existing approaches for damping measures are initiated merely from the point of view of single subsystems, which are independent in their operation. The damping measures are not coordinated with other regions. For example, Power system stabilizers (PSSs) are the most common damping control devices in power systems. The PSSs of today usually rely on local information (such as generator rotor speed or electric power) and are effective in damping local modes. Carefully tuned PSSs may also be able to damp some inter-area oscillations; those which can be observed in the monitored local input signals. However, the observability of inter-area modes in local signals is low, compared to global signals, and therefore limits to a certain extent the effectiveness of PSSs in damping multiple inter-area oscillations.
A recent approach to damp the inter-area oscillations is to utilize a centralized control employing wide area measurement system (WAMS). The major limitation of centralized control is that the communication delay latencies would cause the control signal to have a phase shift that could potentially affect the system stability. Robust controllers that are not impacted by variations such as time delays, which are considered as noise, is one of the solution to address this problem. Another solution is to tune controller parameters using intelligent techniques so that a controller is capable of handling time delays, but this would result in degradation of the controller performance as the settings would have to be changed to cater to the time delays.
For these and other reasons, there is a need for the present invention.